In the prosecution of the parent application, the Examiner has cited thereagainst the following references, i.e., U.S. Pat. No. 4,823,475 issued to Poul E. Hoegh, U.S. Pat. No. 3,726,017 issued to Leslie L. De Mathe, U.S. Pat. No. 1,435,893 issued to H. O. Eiane, U.S. Pat. No. 1,281,790 issued to John Ames Kirk, U.S. Pat. No. 933,798 issued to H. Van Altena, U.S. Pat. No. 781,215 issued to J. T. Leonard, U.S. Pat. No. 684,005 issued to D. T. Stokes, U.S. Pat. No. 471,459 issued to V. M. Ariza, U.S. Pat. No. 1,338,962 issued to E.G. Rios, U.S. Pat. No. 843,374 issued to G. B. Sturgeon, U.S. Pat. No. 328,668 issued to C. S. Gooding, UK Pat. No. 626,014 issued to Robert Cerny, UK Pat. No. 13,302 issued to George Bibby Hartford et al., Japanese Pat. No. 63-88383 issued to Nobuo Hamazaki, German Pat. No. 827,607 issued to Wilhelm Mai, and German Pat. No. 1,032,125 issued to Chi Liang Cho.
The most pertinent references to the paresent application are U.S. Pat. No. 3,726,017 issued to Leslie L. De Mathe, U.S. Pat. No. 4,823,475 Poul E. Hoegh.
U.S. Pat. No. 3,726,017 entitled DRAFTING INSTRUMENT discloses a dial drafting device. According to FIG. 1 thereof, a braking member 34 mounted on the top of the dial drafting device is depicted therein and includes a pivotal brake arm 68 which pivots about a pair of pivot points defined by depending arms 70 which are notched at their lower end for passing through holes in the housing so that they are nonremovably mounted thereto. A resilient braking pad 76 is bonded on the brake arm 68. The lower surfaces of the depending arms 70 define a pivot axis, and the brake arm 68 is attached at one end thereof to a biasing means, such as a helical spring 72, which biases the left end of the brake arm 68 upwardly. A second magnetic member 78 is mounted on the housing so that it extends just below the extreme right end of the brake arm 68 downwardly supplementing the upwardly biasing force of the spring 72 acting on the oppisite end of the brake and thereby enhancing the braking effect of the pad 76 on the wheel 50. To sum up, the braking member 34 normally brakes the wheel 50, so, when the braking member 34 is not to brake the wheel 50, the brake member 34 is to be released by depressing the left end of the brake arm 68.
The drafting device mentioned above has the following main disadvantages:
a) The dial drafting device 34 includes a spring 72 and a second magnetic member 78 as a total biasing means for biasing the left end of the brake arm 68 upwardly. Thus, it is relatively complicated for the producing procedures of the device. PA1 b) For the better use of the drafting device, the device must be always tightly held in order not to get inadvertently translated. The braking member 34 is mounted on the top of the device and the braking member 34 is generally exerting a force perpendicular to the surface of the work piece by the biasing force of the spring 72 and the second magnet 78. Unbraking the wheel 50 by a finger, while translating the device by other finger(s), cannot easily be achieved. Thus, the device cannot be held relatively tightly or easily operated. PA1 c) The braking member 34 is mounted on the fight end of the drafting device and, as mentioned above, the braking member 34 is exerted by a force perpendicular to the surface of the work piece for braking the wheel 50, so this perpendicular force which is not exerted on the longitudinal middle of the device can result in a non-equilibrium of the device. Thus, the working precision of the device is affected. PA1 d) There is a plate 18 receiving some discs on the left end of the device, so it is clear that the draftman cannot easily hold the device. Whereas, it is well known that a drafting device is to be easily held in the draftman's hand so that the draftman can feel ease with the drafting device. PA1 e) The structure of the drafting device is relatively complicated so that the cost of producing this device is relatively high. PA1 a) A brake means according to this invention is manually manipulated by a brake control knob so that the brake function is very hard to be executed when the draftmen is using this instrument. PA1 b) The whole structure of this instrument is too complicated so that the producing cost is relatively high. PA1 c) This instrument is still hard to be tightly held easily.
U.S. Pat. No. 3,726,017 entitled DRAFTING INSTRUMENT discloses a drafting device. This instrument still suffers from the following disadvantages:
It is therefore attempted by the Applicant to deal with the above situation encountered by the prior art.